A group III nitride semiconductor such as gallium nitride (GaN) has advantages of high withstand voltage, high-speed operation, high thermal resistance and low ON-resistance, as compared with the other types of semiconductors such as
Silicon, and hence it is expected that the group III nitride semiconductor is used for a power device. For example, Japanese Laid-Open Patent Publication No. 2011-49741 discloses a driving circuit that drives a GaN field effect transistor (FET) provided as a power semiconductor element.
Also, Japanese Laid-Open Patent Publication No. 2011-44186 discloses a word line driving circuit of a memory cell that includes a capacitor coupling a gate voltage of a FET with a source voltage thereof. A bootstrap circuit driving a signal indicative of a high voltage can be formed by providing a capacitive element such as the above-mentioned capacitor between a gate terminal of a GaN-FET and a source terminal thereof.